Optical communication systems are widely used to transmit information through optical fibers between different regions. An optical communication system may comprise a transmitter, a receiver and a fiber coupled between the transmitter and the receiver. A data stream may be sent to the transmitter in electronic form. The transmitter may encode the data stream onto a light carrier. The light carrier travels down the fiber and reaches the receiver. The receiver converts the optical signal into an electrical signal. Furthermore, the receiver is capable of decoding the electrical signal and reconstructing the original data stream.
The process of converting the data stream in electronic form into an optical signal is implemented through various modulation schemes. The modulation schemes comprise the simplest modulation formats such as on-off-keying (OOK). On the other hand, in order to improve spectral efficiency, a variety of modulation formats have emerged. The newly emerged modulation technologies include phase shift keying (PSK), frequency shift keying (FSK), differential quadrature phase shift keying (DQPSK), dual polarization quadrature phase shift keying (DP-QPSK) and/or the like.
As optical communication technologies evolve, various wavelength division multiplexing (WDM) techniques have emerged as an effective alternative to further improve the transmission capacity of optical communication systems. The WDM technique is able to multiplex a variety of optical carrier signals on a single optical fiber. In other words, the data stream is simultaneously transmitted at multiple carrier wavelengths over a single optical fiber. The WDM based optical systems are widely deployed in a variety of applications such as long-haul networks, undersea networks, metro networks and/or the like.